1. Field of the Invention
The present invention relates to a technique for encapsulating a stator assembly; and more particularly relates to apparatus for use in a submersible pump having an encapsulated stator assembly that provides a watertight seal to electrical components of a stator, a switch and electrical leads and connections coupling these components together.
2. Brief Description of Related Art
Current centrifugal waste water and sump pump technology incorporates a pump that is often assembled utilizing a motor, seals, housing, pump chamber, wire termination, and a separate switch that is responsible for turning the pump on and off, depending on the water level. This technology is susceptible to problems when electrical components come in contact with fluid.
A patentability search was also conducted on embodiments of the present invention and other technology of interest was developed, including, by way of example, the following:
U.S. Pat. No. 7,154,200, which discloses a motor for a hard drive in a computer having an stator assembly having a body of thermoplastic material that encapsulates a stator, where the thermoplastic material has a coefficient of linear thermal expansion such that the thermoplastic material contracts and expands at approximately the same rate as one or more solid parts within or near the body, such as a steel bearing case; and also discloses that its encapsulated stator is formed for arranging inside the rotor of the hard drive motor inside;
U.S. Patent Publication no. US2007/0048157, which discloses a bilge pump having an electric-field effect sensor embedded in its thermoplastic casing for turning the pump on/off depending on the fluid level;
U.S. Pat. No. 3,969,043, which discloses a submersible encapsulated pump and motor assembly, which comprises a molded housing assembly, and includes a process cooled submersible pump and motor assembly and which includes a drive shaft supported by self aligning bearing and motor immersed in coolant fluid;
E. P. No. 09 90 800, which discloses a forced closed-loop cooling for a submersible pump motor, which comprises a sump pump system for electrical motors on submersible pumps that has a motor housing surrounded by coolant jacket;
U.S. Pat. No. 5,466,127, which discloses a device for switching a submersible motor-driven pump on and off, which comprises a submersible pump switching device using external pressure transducer, has adjustable hysteresis in ohmic resistance circuit responsive to pressure on semiconductor overlayer between comb electrodes;
U.S. Pat. No. 6,167,965, which discloses an electrical submersible pump (ESP), which comprises an extensively instrumented with sensors, local processors, and local memory;
U.S. Pat. No. 4,396,353 discloses a submersible sump pump with control system, which comprises an optical sensor to generate signal indicating that water level is sufficient for pump operation;
U.S. Pat. No. 6,481,973, which discloses a variable-speed submersible pump, which comprises a centrifugal pump, with a grinder for entrained solids at the intake, driven by a variable-speed 3-phase AC motor, and which includes a micro-controller which controls the pump output on the basis of sensor data and/or inputs from an external controller, and also monitors the operation of the pump unit and emits alarms and statistical reports as appropriate;
U.S. Pat. No. 5,613,844, which discloses a submersible electronic drive module, which comprises a heat sink for vehicle in-tank fuel pump and includes a drive module wherein said inner layer comprises an elastomeric material molded around said drive module, wherein said elastomeric material is flourosilicone;
WO 02063166, which discloses electronic fluid pump with encapsulated stator assembly, which comprises a fluid pump which includes a pump housing having a housing cavity with an inlet and an outlet and has an encapsulated stator assembly positioned within the housing cavity and at least partially defines a fluid passage from the inlet to the outlet;
U.S. Pat. No. 4,437,811, which discloses a submersible pump with alternate pump operation control means, which comprises a step memory to provide signal at start of pump operation every other time liquid sensor detects liquid level; and
U.S. Patent Publication No. 2005/0214143, which discloses a suction distribution and disconnection system for a submersible pump, including a submersible pump system used that has guide members provided on pump distribution plate and extended from bottom surface arranged relative to opening to facilitate solids entrainment by submersible pump.
There is a need in the industry for a centrifugal waste water and sump pump that is not susceptible to problems when electrical components come in contact with fluid.